This invention relates to a display control device and to a method of operating the display control device.
In desktop computing, it is now common to use more than one display device. Traditionally, a user would have a computer with a single display device attached, but now it is possible to have more than one display device attached to the computer, which increases the usable area for the worker. For example, International Patent Application Publication WO 2007/020408 discloses a display system which comprises a plurality of display devices, each displaying respectively an image, a data processing device connected to each display device and controlling the image displayed by each display device, and a user interface device connected to the data processing device. Connecting multiple display devices to a computer is a proven method for improving productivity.
The connection of an additional display device to a computer presents a number of problems. In general, a computer will be provided with only one video output such as a VGA-out connection. One method by which a second display device can be added to a computer is by adding an additional graphics card to the internal components of the computer. The additional graphics card will provide an additional video output which will allow the second display device to be connected to the computer and driven by that computer. However, this solution is relatively expensive and is not suitable for many nontechnical users of computers.
An alternative method of connecting the second display device is to connect the additional display device to a USB socket on the computer, as all modern computers are provided with multiple USB sockets. This provides a simple connection topology, but requires additional hardware and software to be present, as in general, USB has a bandwidth that makes the provision of a good quality video output a non-trivial task. It is also desirable that any additional hardware between the computer and the display device is kept as simple as possible. This means that when connecting an additional display device using a limited bandwidth technology such as USB, certain complex tasks can be difficult to achieve. In particular, a display control device needs to present that can receive the USB input and provide a suitable output to the display device.
As display technologies improve and the user's desire for display quality increases, the requirement placed upon the display control device that is receiving the incoming display data will correspondingly increase, as the amount of display data will increase proportionally. Since the whole point of the display control device is to provide a cost effective method of adding another display device, it is important that the costs of this device is kept to a minimum. It is obviously desirable that any new display control devices can handle higher definition video inputs and higher resolution display devices, so the ability to produce a high performance display control device at as low a cost as possible is highly desirable.